Control apparatus, network node and method for interchanging data via a data network

A control apparatus (10) comprises an apparatus (12) for ascertaining at least one primary data path (51) between a first (41) and a second (42) data terminal device, which are connected to a data network (60), an apparatus (14) for selecting one of the ascertained primary data paths (51) and an apparatus (16) for ascertaining at least one alternative data path (52i) between the first (41) and the second (42) data terminal device, which alternative data path has no common transmission links with the selected primary data path (51). Furthermore, the invention provides a corresponding network node (20i) and a corresponding method (100).